The invention relates to a cooling device for cooling a metal strip after shaping it in a cold roll mill.
Japanese patent JP-60206516 discloses a cooling device which is arranged between the roll pairs which are arranged along the direction of conveyance of the steel plate M and across the width of the steel plate in multiple cooling units. The coolant heads are situated above and below the thick steel plate M and comprise multiple nozzles arranged at an angle of 30 to 75 degrees in the direction of conveyance.
A cooling device is also known essentially from Japanese publication JP 11129017 A1, for example. The cooling device disclosed there comprises a plurality of nozzles, which are arranged beneath the metal strip to be cooled, each of which sprays a coolant out of a joint tank at a right angle onto the bottom side of the metal strip. After striking the bottom side at a right angle, the coolant moves radially at first out of the way of the underside of the metal strip and/or is displaced radially on the bottom side until at a slight distance from the nozzle, it falls back again from the bottom side of the metal strip into the tank. In the radial displacement, individual particles of the sprayed cooling medium are displaced with one component of movement in the direction of travel of the metal strip while other particles are displaced with one component opposite the direction of travel of the metal strip. The latter particles are exposed to shearing forces in the contact area of the bottom side of the metal strip running in the opposite direction, these shearing forces leading to development of turbulence in these particles of the cooling medium and thus leading to an increased transfer of heat between the metal strip and the cooling medium. The particles of the cooling medium which are displaced in the direction of travel of the metal strip make a much smaller contribution to the dissipation of heat than do the particles displaced in the direction opposite the direction of travel because of the lack of turbulence. Furthermore, the individual particles of the coolant are first decelerated to a velocity Vperpendicular=0 in their perpendicular impact with the bottom side of the metal strip and then are accelerated again in the radial direction. A great deal of energy is lost in this way in the state of the art. The available energy for radial acceleration of the particles is therefore limited, resulting in radial displacement of the cooling medium opposite the direction of travel of the metal strip taking place only on a limited length and/or area. This in turn results in the corresponding cooling area also results in only a small cooling area accordingly. To this extent, the cooling device of the state of the art is ineffective and inefficient.